Completion of certification testing of improved General Electric GEnx-1B engines aimed at meeting Boeing fuel-consumption specifications for the 787 has slipped to “early next year” from the previous fourth-quarter 2012 target. By November 29, some 40 GEnx-1B engines in operation had recorded 33,000 hours and 6,700 cycles, during which they performed better than expected, reported the manufacturer. “The engine [has] demonstrated a two-percent fuel-burn advantage over competitors,” it said in a written response to queries from AIN last week. “We anticipate maintaining this when the [improved] engine enters service.”

Dubbed performance improvement package II (PIPII), the work represents the second element of a two-stage enhancement intended to ensure the GEnx-1B meets fuel-burn requirements and provides the higher thrust needed to support growth in aircraft weight. “We believe the engine is on track with the PIPs to meet original specifications,” said GE. PIP I gained certification in June this year and, together, the two packages should make GEnx-1Bs more durable, permitting longer “on wing” times between overhauls, it added.

GE now anticipates completion of PIPII testing early next year, followed by FAA airworthiness approval “soon after,” according to the company. “[Some] 95 percent of the certification reports [have been done] as we finish up the icing tests,” it said. “We didn’t [have] as much cold weather in Winnipeg earlier this year as we expected, which caused us to delay icing tests until later. But early results have been positive.”

The PIPII package adds various fan, booster, compressor and combustor changes to the low-pressure turbine improvements covered by PIP I, which remains the current build standard. In addition to the 2-percent fuel advantage over other engines, GE believes it will gain another 1-percent advantage from better performance retention.

“Later this year or early next year,” GE plans to begin certification testing of related PIP work for the GEnx-2B engine powering the Boeing 747-8. “We will also begin [the] flight-test program early next year at GE’s Victorville [California] facility,” it said. “We anticipate engine certification mid-2013. The GEnx-2B PIP program will be a more condensed program since it incorporated changes from the GEnx-1B PIPs.”

After 37 flights, GE has completed GEnx-1B PIP-related work on its Boeing 747 flying testbed and has delivered flight-test engines to Boeing. In a six-year development program, GE has tested more than 50 GEnx engines, logging 38,000 ground and flight cycles and accumulating 43,000 hours’ engine-running experience.